Weekend thaw, fairly Arctic Christmas?

Thermometers push across the thawing point across southern Minnesota this weekend. First a minor Clipper brings another 1 to 3 inch snowfall cross central Minnesota into Saturday.

Weekend thaw

Milder pacific air nudges into southern Minnesota this weekend. Temperatures likely stay below freezing up north, but southern Minnesota should see highs into the 30s this weekend. Your car may need some extra blue juice this the next few days.

Snow chances next week?

As I wrote yesterday, it's still too early to bet on any specific snowfall scenario for next week. But most forecast models still favor a low pressure system somewhere in the Upper Midwest next Wednesday or Thursday. The Canadian and European models still bring snow in the Twin Cities next week. NOAA's latest GFS model runs favor snowfall for northern Minnesota.

Here's the Canadian GEM model. Still mostly for entertainment purposes only this far out.

The Twin Cities NWS does a nice job laying out why we express lower confidence in forecasts, and don't bet on specific storm tracks or snowfall totals nearly a week ahead of a possible snow system.

As we say in the weather biz, stay tuned on this one.

Odds of a white Christmas?

Historically, the Twin Cities has a 74-percent chance of at least 1 inch of snow cover on Christmas day. Northern Minnesota is closer to 100-percent.

Here's much more on Minnesota's Christmas snow climatology from the Minnesota DNR Climate Working Group.

Will we have a white Christmas? It's an age-old question that occurs to almost everyone this time of year. The chances of having a white Christmas vary even here in Minnesota. Having a white Christmas is loosely defined as having 1 inch of snow on the ground on Christmas Day. The snow depth at most sites is measured once a day, usually in the morning. The best chances of having a white Christmas is almost guaranteed in the Boundary Waters Canoe Area and a good part of the Arrowhead. The chances decrease to the south and west and the best chance for a "brown" Christmas is in far southwest Minnesota where chances are a little better than 60%. Northern Minnesota is one of the few non-alpine climates in the US where a white Christmas is almost a sure bet (U.S. White Christmas Probabilities).

Arctic Christmas?

How much snow we have on the ground Christmas Day is still an open forecast question. But it still looks colder in the days surrounding Christmas. The upper air pattern continues to support some brand of Arctic air poring south. The 500-millibar upper air maps continue to show a "full-latitude trough" diving south into the central USA around Christmas Day.

The latest GFS model backs off the sub-zero cold around Christmas in the Twin Cities, then brings a surge of milder air in later Christmas week.

I still think lows a few degrees either side of zero look likely in the Twin Cities around Christmas. And low of -20 or colder in northern Minnesota still seem reasonable. Let's see how the models wrestle with the magnitude of the inbound Christmas cold shot in the coming days.